The parent invention of the noted ""819 application relates to crankcase ventilation filters for diesel engines.
Diesel engines have crankcase vents to relieve pressure buildup in the engine. A frequent cause of pressure buildup in the engine is from air leaking past the piston rings into the crankcase. The air that is vented out of the crankcase, also known as blow-by gas or crankcase gas, contains soot and oil mist particles. For many years, the blow-by gas along with the oil and soot was vented to atmosphere through a xe2x80x9croad tubexe2x80x9d to direct the flow to a desired area such as the ground, or away from specific engine parts. In recent years, metal mesh filters have been used to try and remove some of the larger oil droplets from the blow-by stream. These have had mixed results in the field. There have also been after market products which remove oil mist and soot from engine blow-by gas. These products have been designed for industrial and stationary applications, and are usually too large and bulky for mobile applications.
Over the past few years, for appearance and environmental reasons, there has been motivation to eliminate the xe2x80x9croad tubexe2x80x9d type of design, and close the crankcase ventilation system. Closing the crankcase ventilation system means returning the blow-by gas back to the incoming combustion air stream to the engine, for example at the air cleaner or turbocharger. If a closed crankcase system is desired, aerosol sized droplets and mists, which for the most part are ignored in an open system, should be removed. This is desired in a closed system in order to avoid adverse effects on various engine components, especially the turbocharger and after cooler. To do this, a degree of filtration beyond metal mesh is desired.
Packaging a closed crankcase ventilation system in a diesel engine compartment is a problem because of limited space. A closed crankcase ventilation, CCV, system requires routing hoses from the crankcase vent on the engine to the CCV housing, and from the CCV housing to either the dirty side of the air filter or to the turbo inlet of the diesel engine. Furthermore, a drain line needs to be run from the CCV housing back to the oil sump. A xe2x80x9cstand alonexe2x80x9d CCV system will have certain envelope requirements. For example, in a mid-range diesel engine, e.g. 150 to 300 horsepower, a projected envelope size would be a cylindrical housing of about four inches outer diameter and six to seven inches long plus room for connecting hoses, drain lines and valves. In mobile diesel engine applications, finding this amount of space in a convenient location is a problem.
The parent invention provides a diesel engine crankcase ventilation filter addressing and solving the above noted packaging and space problem. The parent invention provides a flat low profile crankcase ventilation filter. In preferred form, the parent invention enables mounting of the flat low profile filter housing directly on the diesel engine valve cover, with minimum space requirements and minimum plumbing requirements.
The present invention relates to a flat panel filter element for a diesel engine crankcase ventilation filter having a flat low profile filter housing extending in a horizontal plane, and more particularly in one preferred form to the sealing mechanism used to seal the element between the valve cover on the engine and the plastic upper housing cover section that is the top of the closed crankcase ventilation system. A plastic frame is provided around a pillow of media with high loft through heat sealing the pillow. Specific media layering and media orientation is enabled. An integral gasket molded to the frame is enabled. A double lip gasket is further enabled. The element removes oil mists and other contaminants from the blow-by gas stream, allowing the effluent gases to be vented into the intake air stream or similar location for the diesel engine. The molded frame is injected molded directly onto the perimeter of the filter media.
In designing a closed crankcase ventilation, CCV, system special care needs to be given to the design of the filter element. The element needs to be efficient enough to protect the components downstream of the element in the system, and have a low enough differential pressure to avoid excessive crankcase pressure, and have sufficient field life, and fit a specific size envelope. Size constraints in a mobile engine compartment dictate a flat panel filter to maximize effect filtering area while staying in the envelope for the engine. The multiple layer media design allows the proper combination of life, efficiency and pressure drop to be used in a CCV system.
The present invention enables an element with three regions of media, each of one or more layers, including a first region providing pre-filtering and consisting of medium efficiency media, a second region of greater efficiency and finer media that removes the oil mists from the blow-by stream, and a third region of coarse media and providing coalescing that allows collected oil to drain through the bottom and shed off of the bottom of the element. The media is oriented for top to bottom flow in the housing. A plastic frame is molded directly to the media. The media and frame are made of similar compounds so no adhesive is required to attach the media and frame. The heat from molding the frame fuses the frame and media together. A gasket provides a seal between the element, both chambers of the valve cover and the plastic CCV cover. The molded frame complements upper and lower plenums in the flat low profile housing. A double lip gasket around the entire perimeter creates a seal by compression and also by deflection of rubber or other gasket material. The gasket defines a seal for the filtration system with multiple chambers. Engine blow-by gas enters the first chamber formed by the valve cover, plastic cover and element seal and then is routed into the upper plenum and then flows downwardly through multiple media layers to the lower plenum. Oil that is captured by the media is released to the bottom of the housing and drained from the system. Air exits the bottom chamber through a separate outlet from the oil drain.